Striation patterns


To observe the effect that different gas pressures have on an electric discharge passed through a discharge tube.


  • A DC power supply
  • A Transformer/Induction coil
  • A set of Discharge Tubes with varying air pressures
  • Connecting wires with appropriate leads


  • When a high voltage is passed through a Cathode Ray Tube, the Cathode emits a ray of electrons.
  • The electrons collide with the gas particles, which excites them.
  • As the excited gas particles are unstable, they emit the energy received as light. (Covered in Quanta to Quarks)
  • As air pressure determines the density of the air particles, the higher the air pressure, the more collisions occur and thus less energy is emitted, which results in different striation patterns.


  1. Connect the system as shown on the diagram.